Rotor for a hover-capable aircraft

Abstract

A rotor is described that comprises: a hub; a plurality of blades; each blade extends along an axis and comprises: a leading edge and a trailing edge; a top surface and a bottom surface, a chord joining points of the leading edge and the trailing edge; and a closed shell made of composite material and adapted to withstand the torque directed along a first axis of the blade; the shell comprises a first and a second element separate from each other, delimiting the respective shell on mutually opposite sides; a first connection element arranged on the side of the associated leading edge and interposed between the first ends of the respective first and second elements; and a third element connected to the associated first and second elements and arranged on the side of the leading edge; the first connection element is connected to respective first faces, and the third element is connected to respective second faces of the first and second elements; the blade comprises a fourth element interposed between the fourth element and the first connection element.

The invention claimed is: 
     
       1. A rotor ( 3 ,  5 ) for a hover-capable aircraft ( 1 ), comprising:
 a hub ( 6 ,  8 ); and 
 a plurality of blades ( 7 ,  14 ) hinged on said hub ( 6 ,  8 ); 
 each said blade ( 7 ,  14 ) extending along an axis (B) and, in turn, comprising: 
 a leading edge ( 20 ) and a trailing edge ( 21 ), opposite to each other; 
 a top surface ( 22 ) and a bottom surface ( 23 ), opposite to each other and extending between said leading edge ( 20 ) and said trailing edge ( 21 ); 
 a chord ( 15 ) joining the points of said leading edge ( 20 ) and said trailing edge ( 21 ) in a section (S) of said blade ( 7 ,  14 ) orthogonal to said axis (B); and 
 a closed shell ( 30 ) made of composite material and adapted to withstand the torque directed along said axis (B) of said blade ( 7 ,  14 ); 
 said shell ( 30 ) comprising: 
 a first and a second element ( 31 ,  32 ), separate from each other, delimiting the respective said shell ( 30 ) on mutually opposite sides and respectively arranged at said top surface ( 22 ) and said bottom surface ( 23 ) of the respective said blade ( 7 ,  14 ); said first and second elements ( 31 ,  32 ) of each said blade ( 7 , 14 ) comprising respective first ends ( 37 ,  38 ) arranged on the side of the associated leading edge ( 20 ) and spaced apart from each other; 
 a first connection element ( 34 ) arranged on the side of the associated leading edge ( 20 ) and interposed between said first ends ( 37 ,  38 ) of the respective first and second elements ( 31 ,  32 ); and 
 a third element ( 80 ) connected to the associated said first and second elements ( 31 ,  32 ) and arranged on the side of the leading edge ( 20 ); 
 said first connection element ( 34 ) being connected to respective first faces ( 100 ) of said first and second elements ( 31 , 32 ); 
 said first faces ( 100 ) being respectively arranged on the opposite side of said top surface ( 22 ) and on the opposite side of said bottom surface ( 23 ) of said blade ( 7 ); 
 said blade ( 7 , 14 ) further comprising a fourth element ( 70 ) interposed between said third element ( 80 ) and said first connection element ( 34 ); 
 characterized in that said third element ( 80 ) is connected to respective second faces ( 101 ) opposite to corresponding said first faces ( 100 ) of said first and second elements ( 31 ,  32 ); 
 said first and second elements ( 31 ,  32 ) of each said blade ( 7 ,  14 ) respectively having, at least in part, a lie substantially parallel to a lie of the corresponding said top surface ( 22 ) and bottom surface ( 23 ) of the blade ( 7 ,  14 ); 
 said first and second elements ( 31 ,  32 ) of each said blade ( 7 ,  14 ) having a thickness in the transverse direction to the lie of the respective said top surface ( 22 ) and bottom surface ( 23 ); 
 said first and second elements ( 31 ,  32 ) respectively comprising a first and a second portion ( 36 ) opposite to each other and having greater thickness than respective remaining parts ( 35 ) of the respective said second and third elements ( 31 ,  32 ); 
 an extension (L) of said first and second portions ( 36 ) parallel to said chord ( 15 ) in said section (S) ranging between 30% and 35% of a length (M) of said chord ( 15 ) in said section (S). 
 
     
     
       2. The rotor according to  claim 1 , characterized in that said first and second elements ( 31 ,  32 ) of each said blade ( 7 ,  14 ) have respective second ends ( 39 ,  40 ) opposite to said first ends ( 37 ,  39 ) and arranged on the side of the associated trailing edge ( 21 );
 said second ends ( 39 ,  40 ) of said first and second elements ( 31 ,  32 ) of each said blade ( 7 ,  14 ) being spaced apart from each other. 
 
     
     
       3. The rotor according to  claim 2 , characterized in that each said blade ( 7 ,  14 ) comprises, on the side of the associated trailing edge ( 21 ), a second connection element ( 33 ) interposed between said second ends ( 39 ,  40 ) of the respective first and second elements ( 31 ,  32 ). 
     
     
       4. The rotor according to  claim 3 , characterized in that said first and second connection elements ( 33 ,  34 ) have, in said section (S), respective open thin-wall profiles, symmetrical with respect to said chord ( 15 ). 
     
     
       5. The rotor according to  claim 3 , characterized in that at least one of said first, second and fourth elements ( 31 ,  32 ,  70 ) and/or said first and second connection elements ( 33 ,  34 ) is made of a composite material. 
     
     
       6. The rotor according to  claim 5 , characterized in that said shell ( 30 ) of each said blade ( 7 ,  14 ) is filled with a foam or honeycomb material ( 41 ) adapted to provide the desired shape to the blade ( 7 ,  14 ). 
     
     
       7. The rotor according to  claim 6 , characterized in that each said blade ( 7 ,  14 ) is devoid of spars. 
     
     
       8. The rotor according to  claim 1 , characterized in that said third element ( 80 ) is arranged in abutment against said fourth element ( 70 ). 
     
     
       9. The rotor according to  claim 8 , characterized in that each said blade ( 7 ,  14 ) comprises a protective element ( 81 ) defining said associated leading edge ( 20 ) and superimposed, at least in part, on the associated said third element ( 80 ). 
     
     
       10. A rotor ( 3 ,  5 ) for a hover-capable aircraft ( 1 ), comprising:
 a hub ( 6 ,  8 ); and 
 a plurality of blades ( 7 ,  14 ) hinged on said hub ( 6 ,  8 ); 
 each said blade ( 7 ,  14 ) extending along an axis (B) and, in turn, comprising: 
 a leading edge ( 20 ) and a trailing edge ( 21 ), opposite to each other; 
 a top surface ( 22 ) and a bottom surface ( 23 ), opposite to each other and extending between said leading edge ( 20 ) and said trailing edge ( 21 ); 
 a chord ( 15 ) joining the points of said leading edge ( 20 ) and said trailing edge ( 21 ) in a section (S) of said blade ( 7 ,  14 ) orthogonal to said axis (B); and 
 a closed shell ( 30 ) made of composite material and adapted to withstand the torque directed along said axis (B) of said blade ( 7 ,  14 ); 
 said shell ( 30 ) comprising: 
 a first and a second element ( 31 ,  32 ), separate from each other, delimiting the respective said shell ( 30 ) on mutually opposite sides and respectively arranged at said top surface ( 22 ) and said bottom surface ( 23 ) of the respective said blade ( 7 ,  14 ); said first and second elements ( 31 ,  32 ) of each said blade ( 7 ,  14 ) comprising respective first ends ( 37 ,  38 ) arranged on the side of the associated leading edge ( 20 ) and spaced apart from each other; 
 a first connection element ( 34 ) arranged on the side of the associated leading edge ( 20 ) and interposed between said first ends ( 37 ,  38 ) of the respective first and second elements ( 31 ,  32 ); and 
 a third element ( 80 ) connected to the associated said first and second elements ( 31 ,  32 ) and arranged on the side of the leading edge ( 20 ); 
 said first connection element ( 34 ) being connected to respective first faces ( 100 ) of said first and second elements ( 31 ,  32 ); 
 said first faces ( 100 ) being respectively arranged on the opposite side of said top surface ( 22 ) and on the opposite side of said bottom surface ( 23 ) of said blade ( 7 ); 
 said blade ( 7 ,  14 ) further comprising a fourth element ( 70 ) interposed between said third element ( 80 ) and said first connection element ( 34 ); 
 characterized in that said third element ( 80 ) is connected to respective second faces ( 101 ) opposite to corresponding said first faces ( 100 ) of said first and second elements ( 31 ,  32 ); 
 each said blade ( 7 ,  14 ) being devoid of spars; 
 said shell ( 30 ) of each said blade ( 7 ,  14 ) being filled with a foam or honeycomb material ( 41 ) adapted to provide the desired shape to the blade ( 7 ,  14 ). 
 
     
     
       11. The rotor according to  claim 10 , characterized in that said fourth element ( 70 ) of each said blade ( 7 ,  14 ) is made of composite material and laminated parallel to said axis (B). 
     
     
       12. The rotor according to  claim 10 , characterized in that said fourth element ( 70 ) of each said blade ( 7 ,  14 ) is solid. 
     
     
       13. A hover-capable aircraft ( 1 ), comprising at least one rotor ( 3 ,  5 ) according to  claim 1 .